Transient nuclear criticality excursion analysis of highly dispersed particulate three-phase fluidised systems

The aim of this study was to perform sensitivity analysis, investigating how different fluidisation and sedimentation characteristics three-phase wetted UO2 powder beds, may affect a transient nuclear criticality excursion initiated through the addition water into fissile bed. This type postulated accident scenario occur in fuel fabrication facilities when fire is fought use water, supplied via an automatic or manual fire-suppression system. A similar also develop as result leaks flooding process area housing powder. article introduces model for gas-bubble induced bed examines phenomenon neutron kinetic response fluidised Empirical analysis has shown that suspensions form agglomerated structures suspended at agglomerate sizes range from 18 μm 40 μm. Simulation results indicate both critical gas velocity rate significantly dynamics. re-distribution mass highly dispersed suspension generally reduces reactivity system, however, depending on H/U ratio, positive be added Low Péclet numbers suggest motion causes dispersive flow field. An oscillatory power predicted low velocities where system predominantly governed by within frequency these oscillations greater higher hindered settling particles. At velocity, voidage feedback, making quite independent fluidisation. In all cases, large volumes leave domain due overflowing suspension. Transient excursions beds with are terminated once becomes fully saturated.